Sheet positioning and clamping means



May 20, 1952 A. PLEYDELL ET AL SHEET POSITIONING AND CLAMPING MEANS Filed April 27, 1950 INVENTORS 'AZ5ZKT/ ZH UFLZ BY R055 PLfKDfZZ 4 FIG. 5

Patented May 20, 1952 UNITED STATES PATENT OFFICE SHEET POSITIONING AND CLAMPING MEANS Albert Pleydell and Rose Pleydell, Bellerose, and Jean F. McIntyre, Flushing, N. Y.

Application April 27, 1950, Serial No. 158,536

3 Claims. (Cl. 101-126) This invention relates to sheet positioning and clamping means. More particularly, the invention concerns the combination of a work supporting base and combined means for accurately positioning sheet material on the base and clamping the positioned sheet material on the base.

In the printing or graphic arts where sheet materials must be positioned on a base to receive an imprint thereon, it is desirable that guide or gauge means be provided for accurately positioning the sheet material on the base. This is particularly necessary in the silk screen process when sheets are to be printed with more than one color in accurate registry with one another. In this art it is conventional to provide the base of the silk screen printer with register guides in the form of paper or carboard tabs. Such guides require frequent replacement and change when there is a variation in the thickness of the sheet material being printed.

Accordingly, an object of this invention is to provide a base having a work supporting surface with improved, movable guide means thereon for accurately positioning a sheet on the work supporting surface, the guide means being movable to a position to clamp the sheet to the work supporting surface.

Another object of this invention is to provide in a silk screen printing device, movable gauge means for accurately positioning a sheet on the base thereof, the gauge means including clamping means for retaining the positioned sheet on the base, together with means for effecting movement of the gauge means to its clamping position, together with means for controlling the operation of the gauge moving means, the control means being responsive to the movement of the silk screen frame portion of the device toward and away from the base portion thereof.

Still a further object of this invention is to provide a base having a plurality of sheet gauging and clamping members movably mounted thereon, selected members being adapted to be moved from a sheet gauging position to a sheet clamping position while other members are moved to a non-functioning position wherein the other members do not interfere with the placement of a sheet on the base or the operation of the selected members.

Yet another object of this invention is to provide sheet positioning and clamping means which is of simple construction, of a rugged nature, and eficient to a high degree in use.

Other objects of this invention will in part be obvious and in part hereinafter pointed out.

The invention accordingly consists in the combination of elements and arrangement of parts, which will be exemplified in the devices hereinafter described, and of which the scope of invention will be indicated in the following claims.

In the accompanying drawing, in which is shown illustrative embodiments of the invention:

Fig. 1 is a perspective view of a device embodying the invention; 1

Fig. 2 is a longitudinal section of the base portion thereof, with parts broken away;

Fig. 2-A is a portion of the longitudinal section shown in Fig. 2, with the sheet positioning and clamping means shown in its elevated position;

Fig. 3 is a wiring diagram showing the connections for the operating means of the device;

Fig. 4 is a partial longitudinal section of the device, showing a modification thereof; with the sheet positioning and clamping means in its depressed position;

Fig. 5 is a sectional view similar to that of Fig. 4, with the sheet positioning and clamping means in its elevated position and Fig. 6 is a wiring diagram showing the connections for the operating means of the device shown in Figs. 4, 5.

Referring in detail to the drawing, and particularly to Fig. 1, Iil designatesa silk screen printing device. The same comprises essentially a rectangular shaped base I I to which is hingedly connected the silk screen frame I2 on which stencil Sis mounted, in the usual manner. The frame I2 is adapted to be moved towards and away from the base I I, as a part of the printing cycle, in a manner well known in the art.

The base I I comprises a top wall which presents a smooth, planar work supporting surface I3, a bottom wall I4, side walls I5, I5a, and end walls I6, I611. The top wall has longitudinal edges I'I. IIa and transverse edges I8, I8a. The frame I2 is hinged to base II along edge IT, in a manner known in the art. The surface I3 includes longitudinal marginal portions I9, I9a. and transverse marginal portions 20, 20a.

Sheet material A, which may be rectangular in shape, is adapted to be positioned on surface I3 in order to receive on its upper surface an imprint by way of the stencil S on frame I2, when the frame is lowered into contact therewith and color is applied to the interior of the frame, in a known manner. Means is provided for accurately positioning the sheet A relative to the surface I3. To this end. there is provided an angular gauge and clamp member 2| which is movably mounted in marginal portion of surface l3. A plurality of such members may be arranged in longitudinal alignment with one another, as shown in Fig. 1. Similarly, one or more angular gauge and clamp members 22 are movably mounted in marginal portion IQ of surface |3. The members 22 are similarinall respects to members 2|.

Each of the :members .2| is :in the form of *.-a right angle, having a vertical leg 23 and ahorizontal leg or lip 24. The members 2| may be made of thin gauge steel or other suitable material. The legs or lips 24 may beitapered itoward their outer ends, which are disposed toward the centre of the surface |3.

The marginal portion 20 ofsurface'il3;isiformed with an elongated slot 25 for each of the members 2 l. The slots are longitudinallyaligned.andsdisposed parallel to edge l8. Each of theslots. 25 is provided with a rectangular bearing sleeve 26 for ,slidably receiving the leg 23 of members 2|. Theupper ends 'of'sleeves 26 are-'fiush'withthe surfaceil3. "The sleeves26 are accurately aligned relativeto each other so that the'innersurfaces 23a on legs "23 are disposed in a commonplane. With the members 2| in their raised position, as shown inFig. 2A, the surfaces 23a provide gauge mfiansadapted to be abuttedby the left hand edge B of sheet A, as the sheet is moved across surface 13.

The members 22 aremovably mounted in marginal portion I9 of surface l3, in the manner described ,in connection with members 2|, the legs 23 of .membersz'z being disposed parallel to edge l1. The gauge surfaces 23:: on the members 22 are also disposed .in a common plane. Additionally, the members 122 .are accurately located bynreans of their bearing sleeves 26, so that the plane including the surfaces 23a of members 22 intersects the plane including the surfaces 23a of members 2| precisely at 90. 'With the members 2|, 22 in their raised position, sheet A may be moved oversurface l3 to bring the adjacent sheet edges B, B into abutment with the gauge surfaces of the respective members, thus accurate y locating the sheet as a Whole, relative .to the surface |3.

.As shown in Fig. 2A,- when the sheet A is properly positioned on surface l3, the legs or lips 24 of the ,members 2|, 22 will overlie the marg'inal portions of the sheet. 'The members 2|, 22 are adapted to be moved downwardly so that legs 24 thereof will clamp sheet ,A in its proper ppjsitionon surface I3.

To this end there is mounted on-bottom wall ll of the base a solenoid 21 beneath eachof themembers 2|, 22. Each solenoid comprises a coil 28 .and a vertically disposed, slidable plunger 23 whichhas a slotted upper end 30. The leg23 of each mernber 2|, 22 is received at its lower end in the slot 30 of a corresponding plunger 29. A cross pin 3 links each member to its operating plunger. The .members 2|, 22 are raised to their normal, elevated position, as shown in Fig. 2-.A, by means of a spring 32 anchored at one end to the underside of the top wall of the base and attached at its other end to a lateral projection .33 on solenoid plungers 29. With the members 2|,. 22 raised to their elevated position, legs 24 thereof are disposed in substantially parallel relationto surface I3.

The coils 28 of the solenoids are connected in parallel with each other and with a source of current which may take the form of a battery 34, as indicated in Fig. ,3. A normally open button switch is connected between current source 34 and the interconnected coils 28. The switch 35 may be located on the underside of the top wall of the base, being disposed in marginal portion l9 and adjacent edge [1. The operating button portion 36 of the switch projects upwardly through a suitable opening in the top wall.

It willbe apparent that uponproperlylocating sheet A on surface l3 by means {of the gauge Surfaces 2'3a'on m'embers2 ,'22,"thesh'ee't is ready .to be printed. Accordingly, the frame I2 is lowered to its working position to bring stencil S :intocontact-withrsheet A. As the frame is being lowered, the button 36 of switch 35 is engaged by the opposedportion of the frame and pressed downwardly to "close the circuit which energizes the solenoids 21. This will cause members 2|,,

r22 ito ,;move downwardly through the movement of the interconnected plungers 29, thereby moving legs 24 of the members to clamp sheet A againstsurface I3. The clamping action of members 2], "'22 will rbe;contr'o1led due to the "action of springsj32, thus avoiding crease marks-on=the sheet A. 'When the printing :step iscompleted and 'frame I2 is raised in the usual manner, switch 35 will be operated to open the circuit and deenergize the solenoids, thus allowing springs 32 .to raise members 2|,, 22 totheir elevated position. The sheet A may then be readily removed and replaced by a new. sheet which ispositioned and clamped in the'manner previously described.

It will be apparent that with the gauge surfaces 23a on members 2|, 22 permanentlylocated relative to surface I 3, each sheet-will be accuratelypositioned on'the surface l3 and theimembers taking care of sheets of varying thickness. "When a previously printedsheet is returned for application of other colors, accurate registrationis made possible by the members '2 22. 'Inadditi'on, the members in their clamping position, eliminate the possibility of accidental movement .of the sheet on surface 3.

The number, spacing anddimensionsof members 21,22 maybe varied to suit thesi'zje-of the base H and the dimensions of the sheets to be printed. ,If desired a single set of gauge and clamp members may be used to 'p'ositi'onand clamp one edge only of a sheet, or .a setof members may be used in conjunction with {a fixed guide tojposition adjacent edge of thes'het.

The legs 2'4-on members 2 22 willnot interfere with the actionof the silkscreen frame. 112 during the printing operation due to the thlnnessof the legs and the fact that theyare disposed in the marginal portions of theshee'tg'a.

In a modified form of the invention, selected members I2|., 22 may be arranged to fhavetheir legs 24 depressed into recessed portions ofsurface l3, thus presentingv smooth planar surfaces in the marginal as well as the central portions of surface 13. This .is advantageous .in cases where sheets are to be printed which have substantially reduced dimensions and therefore, .requiring a limited number of themembers 2|, '22 for gauging and clampingthe same. .Also, if only one set of members are to be used, it would be desirable to depress the other set of members to a non-operating position. In addition it"may be desired to depress one ormore of the members in order to facilitatethe movement of sheet A over surface I3.

Accordingly, as shown in Figs. .4, 5, the surface I3 is formed with recesses 40 which are complementary to the legs v24 of the members 2|, 22 and ad'ap't'ed to receive the legs when the members are moved to their depressed position.

As shown in Fig. 4, the upper surface of leg 24 is then substantially coplanar with surface [3. Each of the recesses 40 is provided with a com plementary shim 4| which may be removably placed therein. The shims M are placed in the recesses of those members 2|, 22 which are to be used to gauge and clamp a sheet. Since the shims present a surface coplanar with surface 13, as shown in Fig. 5, they provide a clamping surface for the coacting legs 24 of the members.

It is also desirable that the non-working members 2 I, 22 be adapted to be moved to bring their legs 24 into their corresponding recesses 40, before the sheet A is positioned on surface l3. To this end, the solenoids 2'! are wired as shown in Fig. 6. The solenoid coils 28 are connected together on one side to one side of battery 34 and each of the coils is separately connected on its other side to the movable switch blade 42 of a double pole switch 43. The fixed contacts 44 of the switches are connected together and are connected to one side of button switch 35. The other fixed contacts 45 of the switches are connected together and interconnect the other side of switch 35 and the other side of battery 34. The switches 43 may be suitably mounted on wall I511. of the base H for selective manual operation, the switch blades 42 being normally left in engagement with switch contacts 44.

Any one of the solenoids 21 may be independently energized by operating the corresponding switch 43 to move blade 42 into engagement with its contact 45, independently of the operation of button switch 35. Accordingly, each of the non-operating members 2|, 22 is initially lowered by operation of their corresponding switches, thus bringing their legs 24 flush with surface 13. Shims 4| are placed in the recesses 40 of the operating members. After positioning sheet A on the surface l3, in the manner previously described, the frame I2 is moved down, thus operating switch 35 to energize the solenoids of the operating members 2|, 22 and to thus clamp the sheet, as previously described.

It will thus be seen that there is provided sheet positioning and clamping means in which the several objects of the invention are achieved and which is well adapted to meet the conditions of practical use.

As various possible embodiments might be made of the above described invention, and as various changes might be made in the embodiments set forth, it is understood that all matter herein set forth or shown in the accompanying drawing, is to be interpreted as illustrative and not in a limiting sense.

Having thus described our invention, we claim as new and desire to protect by Letters Patent:

1. In a device including a base having a work supporting surface and a frame member movably mounted relative thereto, a member movably mounted on said baseand including a gauge surface for positioning a sheet on said work supporting surface, said member including a portion for clamping said positioned sheet to said work supporting surface upon movement of said member in one direction, electromagnetic means operatively connected to said member for moving said member in said direction and switch means in circuit with said electromagnetic means operable by said frame member for controllng the operaton of said electromagnetic means.

2. In a silk screen printing apparatus comprising a base having a work supporting surface and a silk screen frame mounted for movement towards and away from said surface, sheet gauging means on said base comprising an angular member having a pair of legs substantially at right angles to each other, said means being arranged whereby one of said legs is movable in a direction substantially at right angles to said surface, while the other leg is disposed substantially parallel to said surface, a solenoid including a movable plunger, means for operatively connecting said plunger to the first mentioned leg of said gauging means, said solenoid being adapted to be energized to move the plunger thereof in a direction to bring the'second mentioned leg of said gauging means toward said work supporting surface, a switch in circuit with said solenoid for controlling the movement of the plunger thereof said switch including operating means adapted to be engaged by said silk screen frame upon movement thereof toward said work supporting surface.

3. In a silk screen apparatus comprising a base having a planar work supporting surface and a silk screen frame mounted for movement toward and away from said surface, a plurality of members movably mounted on said base and disposed in normally elevated position, each of said members including a gauge surface extending substantially at right angles to said work supporting surface and a clamping portion extending substantially parallel to said work supporting surface, said base being formed with a recess for receiving the clamping portion of each of said members upon downward movement of said members whereby the upper surfaces of the clamping portions of said members will be substantially coplanar with said work supporting surface, means for moving each of said members downwardly,

means for controlling the operation of selected member moving means, and means responsive to the movement of said frame toward said work supporting surface for controlling the operation of the remaining member moving means.

ALBERT PLEYDELL. ROSE PLEYDELL. JEAN F. MCINTYRE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain Aug. 20, 1920 

